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During cold weather with low outdoor dew points (<50^F), adequate fresh air change should maintain low inside humidity. Therefore a damp home during cold weather indicates inadeauate fresh air ventilation to purge indoor air pollutants and renew oxygen. As weather warms, fresh air infiltration, decreases. Fresh air ventilation is basic in any home when occupied.
Yes, a dehumidifier is necessary when the outdoor dew points are +55^F to maintain <50%RH inside during low/no cooling load conditions.
Ultra-Aires are the grand daddy of whole house dehumidifiers with the best air filters, lowest electrical usage (highest Energy Star rating) and most durable.
I have worked for Ultra-Aire for 20 years. These are priced on the high end. Any distributor or contractor can order a unit from 800 533 7533.
Thanks for the support.
Regards TB

Thanks for your reply. My home is roughly 2200 sq ft heated/cooled. Which model do you think that I would need, the 90?

4 occupants. Is there a separate tstat for running the UA? Does the UA run through all of the existing ductwork? How noisy is the machine?

Thanks

Chad

The UA line uses the DEH 3000 controller for controlling fresh air and %RH.
Many duct options, Using all the a/c ducts to supply dry throughout the home. Noise is like a refrigerator. Isolating the UA with flex duct and sound board make the unit acceptable. It has a small a/c compressor and fan that is surrounded with an insulated cabenit. The fresh air inlet is a dampered insulted 6" flex duct. You need 60-80 cfm of fresh when the home is occupied and the winds are calm.
Regards TB

I've just read this, and what I find odd is his outdoor temps of 40F just do not equate to massive humidity collection on the windows... assuming his cooking hood is vented to the outside, not just blowing back into the kitchen, moisture has to be coming in from somewhere. turning on the heat should NOT raise the humidity level, it should lower it. if a HUMIDIFIER is in the furnace ductwork, that could account for it, as I've seen plenty of spray bar types installed with the humidistat locked full on... so as soon as temps rise, the thing starts spraying.
I recommend to the homeowner to have a tech come look at the equipment to see if there is a humidifier on the furnace. and if so, where is the humidistat set?
tight homes sure do hold on to moisture, but tight DUCTWORK should not amplify it... unless there is a moisture source. puddles of water in the winter just do not make sense to me.
is this house insulated with icynene foam? is the attic sealed with foam? is the ductwork being soaked with water?
I'm not convinced it's solely from living in the home building up moisture. 40F is just not cold enough to cause that kind of condensation on the windows... unless there is water being DUMPED into the house.
those standalone dehumid's have a 3 gallon capacity... that's a LOT of winter humidity!

The TRUE highest cost system is the system not installed properly...
The three big summer hearththrobs...
Mel Gibson
Dwane Johnson
The A/C repairman

I've just read this, and what I find odd is his outdoor temps of 40F just do not equate to massive humidity collection on the windows... assuming his cooking hood is vented to the outside, not just blowing back into the kitchen, moisture has to be coming in from somewhere. turning on the heat should NOT raise the humidity level, it should lower it. if a HUMIDIFIER is in the furnace ductwork, that could account for it, as I've seen plenty of spray bar types installed with the humidistat locked full on... so as soon as temps rise, the thing starts spraying.
I recommend to the homeowner to have a tech come look at the equipment to see if there is a humidifier on the furnace. and if so, where is the humidistat set?
tight homes sure do hold on to moisture, but tight DUCTWORK should not amplify it... unless there is a moisture source. puddles of water in the winter just do not make sense to me.
is this house insulated with icynene foam? is the attic sealed with foam? is the ductwork being soaked with water?
I'm not convinced it's solely from living in the home building up moisture. 40F is just not cold enough to cause that kind of condensation on the windows... unless there is water being DUMPED into the house.
those standalone dehumid's have a 3 gallon capacity... that's a LOT of winter humidity!

Thanks for all of the replies. My home is not insulated with foam, but with sprayed cellulose in the walls and blown cellulose in the attic. As far as I know, there is not a humidifier in the ductwork. Nothing fancy about my system, just a Trane 16 seer heat pump. What should be my next step to take? Should I have a test done to see if I have any leaks in the ductwork or to see if moisture is infiltrating anywhere? Sorry, but I don't know any of the terms used in the hvac business. Anyway, just say that checks out ok with no leaks. Would a whole house deumidifier, like the ultra aire 70 be my best bet? Again, I really appreciate all of the advice being given.

I'd think that the RH has been high for a while, at least since a/c hasn't been used.
finally it built up to a point to manifest itself in condensation on the windows.
in the summer, folks don't usually notice condensation because it is on the
outside of the windows. it is usually noticable in the mornings & evenings depending
upon how much sun the windows get.

if cellulose in walls was wet blown...that is more humidity until it dries out. usually
waiting several days before sheetrocking is done is sufficient...but without
moisture meter readings..who knows? over time it will dry.

once excessive moisture is removed, dehumidifier will not need to be emptied
as often.

it wouldn't be a bad idea to have a blower door test on the house, and duct leakage
test for ductwork & returns. usually this isn't hvac contractor, but an energy rater
or auditor.www.resnet.us lists most active raters nationwide.
BPI and Comfort Institute also do these types of tests.

getting the tests..is just part of the procedure.
sealing leaks in house, ducts & returns still needs to be done.
usually we (raters) test before and after to measure what was achieved.

on an average 20-30% duct/return leakage isn't uncommon. so there
almost always room for improvement.

when you call OP, you want to have a diagnostic test of house & ducts/returns.
explain the high RH issues. and any other issues you have.

I have the ultra aire 70, my house is 1,000 sq ft.
mine is tied into the supply plenum, and I built a box around it
out of ductboard because it is located in a closet off the living room.
I hardly notice it at all when it runs.

btw...what about the water heater? I know tips is wanting to know.
where is it located...what type.
also, do you have recessed lights? inquiring minds want to know!

best of luck

The cure of the part should not be attempted without the cure of the whole. ~Plato

I'd think that the RH has been high for a while, at least since a/c hasn't been used.
finally it built up to a point to manifest itself in condensation on the windows.
in the summer, folks don't usually notice condensation because it is on the
outside of the windows. it is usually noticable in the mornings & evenings depending
upon how much sun the windows get.

if cellulose in walls was wet blown...that is more humidity until it dries out. usually
waiting several days before sheetrocking is done is sufficient...but without
moisture meter readings..who knows? over time it will dry.

once excessive moisture is removed, dehumidifier will not need to be emptied
as often.

it wouldn't be a bad idea to have a blower door test on the house, and duct leakage
test for ductwork & returns. usually this isn't hvac contractor, but an energy rater
or auditor.www.resnet.us lists most active raters nationwide.
BPI and Comfort Institute also do these types of tests.

getting the tests..is just part of the procedure.
sealing leaks in house, ducts & returns still needs to be done.
usually we (raters) test before and after to measure what was achieved.

on an average 20-30% duct/return leakage isn't uncommon. so there
almost always room for improvement.

when you call OP, you want to have a diagnostic test of house & ducts/returns.
explain the high RH issues. and any other issues you have.

I have the ultra aire 70, my house is 1,000 sq ft.
mine is tied into the supply plenum, and I built a box around it
out of ductboard because it is located in a closet off the living room.
I hardly notice it at all when it runs.

btw...what about the water heater? I know tips is wanting to know.
where is it located...what type.
also, do you have recessed lights? inquiring minds want to know!

best of luck

Thanks for your input. Yes I do have recessed lights. As a matter of fact, that is all I have. Also, I have 2 water heaters that are located in the attic. They just look like ordinary water heaters to me.

Actually this home was completely gutted about a year ago due to having Chinese drywall. Since I was basically the contractor and sub contracted everything out, I just don't know what to think. Obviously we never had this problem the first time we built this home. The house has a constant musty smell in between cooling and heating seasons, so I take it that this is where the high humidity is coming into play.

Also consider that occupants release about .5 lbs. of moisture per hour into the space from respiration, presperation, and activities. 2 lbs. of moisture per hour into a 2,200 sqft of space will raise the %RH 7-8%RH/ hour if there is no fresh air moving through the home. If the home was absolutely air tight, the home would be 100%Rh. Of course it is not but you have an indication of a lack of fresh air ventilation. 60-80 cfm of fresh <50^F dew point outside air will purge indoor pollutants, renew oxygen, and keep the home dry.
You need this amount of fresh air whenever the home is occupied to maintain high indoor air quality. When the outdoor dew points are +55^F, you need supplemental dehumidification to remove the moisture in the fresh air and from the occupants. During high cooling loads, the a/c will keep the home <50%RH. During low/no cooling loads, the dehumidifier will maintain <50%RH. Why is this so hard to figure out?
Regards TB